.header {
  background-color: #f2f2f2;
  padding: 20px;
  text-align: center;
}

ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: #333;
}

li {
  float: left;
}

li a {
  display: block;
  color: white;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

li a:hover:not(.active) {
  background-color: #111;
}

.active {
  background-color: #4CAF50;
}

form {
  width: 50%;
  margin: 0 auto;
  padding: 20px;
  border: 1px solid #ddd;
  border-radius: 4px;
}

label {
  display: block;
  margin-bottom: 8px;
}

input[type="text"], input[type="email"], select {
  width: 100%;
  padding: 6px 10px;
  margin: 8px 0;
  box-sizing: border-box;
  border: 1px solid #555;
  border-radius: 4px;
  font-size: 16px;
}

button[type="submit"] {
  padding: 10px;
  background-color: #4CAF50;
  color: #fff;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}

button[type="submit"]:hover {
  background-color: #3e8e41;
}

table {
  border-collapse: collapse;
  width: 100%;
}

th, td {
  border: 1px solid #ddd;
  padding: 8px;
  text-align: left;
}

th {
  background-color: #f2f2f2;
}

tr:nth-child(even) {
  background-color: #f2f2f2;
}

.header {
  background-color: #f2f2f2;
  padding: 20px;
  text-align: center;
}

a {
  text-decoration: none;
  color: #333;
}

.add-button {
  margin-bottom: 20px;
  padding: 10px;
  background-color: #4CAF50;
  color: #fff;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}

.add-button:hover {
  background-color: #3e8e41;
}